Astronomers searching for asteroids headed toward Earth have
stumbled upon a harmless but fascinating discovery -- an
exploding star, also known as a supernova.

The supernova, named 1999am, is located in a galaxy about
650 million light-years away. (A light-year is the distance
light travels in one year, about 9.5 trillion kilometers or 6
trillion miles.) The star was unknown to astronomers until it
was captured by the camera on NASA's Near Earth Asteroid Tracking
(NEAT) system on February 18. The NEAT images show the star as
it looked just a few weeks after the ancient explosion took
place.

"We were fishing for salmon, and instead we caught a whale,"
said Dr. Steven Pravdo, project manager and co-investigator for
NEAT. "The project is designed to look for asteroids and other
objects that might pose a potential hazard to Earth. This
supernova discovery is an added bonus for astronomers in
general."

Supernova 1999am is a "Type Ia supernova," which means that
before it exploded, it was a white dwarf star in orbit with a
companion star. Near the end of its life, the white dwarf
captured so much material from its companion that it became too
massive to support itself, and exploded with as much energy as
100 billion suns. The supernova is now nearly as bright as the galaxy
surrounding it, which is known as CGCG 060-009.

NEAT, with asteroid hunter Eleanor Helin as principal
investigator, has been in operation since December 1995. It uses
a large, sensitive and fully automated charge- coupled device
(CCD) camera mounted on a 1-meter-diameter (39-inch) telescope.
The telescope is operated by the U.S. Air Force atop Mt.
Haleakela on the island of Maui, HI.

Since the middle of 1998, NEAT scientists have posted their
data on a web site through a program called SkyMorph, a
collaboration between JPL and NASA's Goddard Space Flight Center,
Greenbelt, MD. While the NEAT project detects Earth-approaching
objects by looking for celestial bodies that move over a period
of time, the data can be used also to hunt for stationary objects
that become brighter or dimmer over time. Thus, the images
present a smorgasbord of astronomical options -- NEAT scientists
pick out asteroids, while other astronomers select various cosmic
morsels through the public SkyMorph web site.

"Through SkyMorph, astronomers may find an array of
interesting objects, including supernovae," said Pravdo,
principal investigator for SkyMorph. "In this case, we sent our
data directly to the Lawrence Berkeley National Laboratory in
Berkeley, California. Dr. Greg Aldering and other scientists
with their Supernova Cosmology Project immediately found 1999am."

Pravdo said the Lawrence Berkeley National Laboratory
scientists found the supernova by comparing images taken in
February with previous NEAT data. They could clearly see a
change in brightness, indicating the star had exploded and become
a supernova. They further confirmed their finding with
additional observations by ground-based telescopes. February 18
marked the first time NEAT scientists forwarded new data directly
to the Berkeley lab, and as Pravdo pointed out, "We struck
paydirt."

Dr. Thomas McGlynn is lead scientist for SkyMorph at
Goddard. The NEAT and SkyMorph projects are managed by JPL for
NASA's Office of Space Science, Washington, DC. JPL is a
division of the California Institute of Technology, Pasadena, CA.

For more information, go to http://www.jpl.nasa.gov.
JPL is a division of the California Institute of Technology, Pasadena, CA.